This invention relates to a trim arrangement for an outboard motor and more particularly to an improved trim pin arrangement for such applications.
As is well known, outboard motors are normally mounted on the transom of an associated watercraft by means of a clamping bracket that is connected in some manner to the transom. A swivel bracket is pivotally connected to the clamping bracket and mounts the propulsion device. The pivotal movement permits a trim adjustment of the propulsion device. The propulsion device is, in turn, supported by the swivel bracket for steering movement about a generally vertically extending steering axis.
It is the normal practice to employ in the clamping bracket a series of spaced-apart apertures that are adapted to receive a trim pin. This trim pin is abuttingly engaged by the swivel bracket and sets the trim condition of the propulsion device, depending upon which of the pair of apertures it is received in.
There are some disadvantages with this type of construction, which may be best understood by reference to FIGS. 1, 2, and 3, which depict three different types of prior art trim adjustment mechanisms. In each of these figures, a clamping bracket is indicated generally by the reference numeral 11 and the tilt pivot pin is identified by the reference numeral 12. Although the swivel bracket is not shown, it is to be understood that it is pivotally mounted on the tilt pivot 12 in a well-known manner. In order to permit trim adjustment, a series of apertures 13 are formed in the clamping bracket 11, and particularly outstanding leg portions thereof, to receive a trim pin, which is engaged by the swivel bracket in the manner aforedescribed so as to adjust the trim condition. This extending portion of the clamping bracket is identified by the reference numeral 14 in FIGS. 1-3, and it will be seen that the three figures illustrate three different types of arrangements along which the trim apertures 13 may be formed.
Referring first to FIG. 1, the apertures 13 are disposed so that their centers lie along an arc, indicated by the reference numeral 15, which arc is drawn at a radius R1 which passes through the center of each aperture and which has at its center the center or pivot axis defined by the tilt pivot pin 12.
FIG. 2 shows another arrangement, and this differs from the arrangement of FIG. 1 only in that the trim apertures 13 and the extending portion 14 are disposed lower on the clamping bracket 11. Hence, the arc 15 upon which the center of the apertures 13 lies is at a greater radius R2 than the radius R1 of FIG. 1.
In the third type of embodiment, there are provided pairs of apertures 13 which are disposed in the projection 14 at two different radii, one, R3 on an arc indicated by the line 16, and the other having a radius R4 lying on the arc 17. The radius R3 passes through the lowermost aperture 13 and through the centers of all of the other apertures on the arc 16. In a similar manner, the radius R4 passes through the center of the lowermost aperture on the arc 17, and all other apertures of this series lie on the same radius.
The prior art constructions as thus far described have two disadvantages. As may be seen from the figures, the projections 14 extend rather substantially rearwardly from the sides of the clamping bracket 11. As a result, they will be contacted by the drive shaft housing of the outboard motor, in a manner which will be described later by reference to the preferred embodiments of the invention, and limit the total degree of steering possible. In addition, the arrangements are such that the trim pin that is received in the apertures 13 will contact either the same or substantially the same area on the swivel bracket regardless of the trim adjustment. This is an area which is subject to wear, and accordingly, the prior art constructions have the effect that the trim axis will change as the swivel bracket becomes worn, and this wear is accelerated due to the contact always at substantially the same place.
It is, therefore, a principal object of this invention to provide an improved trim adjustment arrangement for an outboard motor.
It is a further object of this invention to provide an improved trim arrangement for an outboard motor that is compact in nature without sacrificing the range of adjustment and without interfering with the range of steering movement of the outboard motor.
It is a still further object of this invention to provide an improved trim arrangement for an outboard motor wherein the point of wear is shifted when the trim position is shifted so as to minimize the amount of localized wear that will occur on the outboard motor in the trim adjustment area.